Her name is Elizabeth MacDonough. A graduate of ultra-liberal Vermont Law School, she was tapped by Senator Harry Reid to be the Senate parliamentarian in 2012. Now, as long as the Senate Republicans allow it, she can decide the fate of the efforts to repeal and replace the Affordable Care Act.

Her job right now is to determine which elements of the Republican Obamacare replacement bill are budgetary and which are normal legislation. Only the parts she deems to be budgetary are allowed to pass with only a simple majority. The rest requires 60 votes, a political impossibility in the current environment.

At issue is the list of 10 "essential" services that the Obamacare statute requires be included in any health insurance plan offered through the exchanges. This list drives premiums and deductibles up to levels most people cannot afford, forcing them to opt out of the system. A downward spiral ensues: The risk pool becomes sicker and older, and the premiums keep going up, further reducing the pool of the young and the healthy.

Given her liberal roots, MacDonough is likely to rule that 60 votes are needed to dilute the requirement, which would be fatal to reform. If the Senate passed the reform bill without cutting the required services, the new system would fall victim to the same spiral that doomed the old one, leaving the cost too high and the ranks of the insured too thin.

What most younger couples want is catastrophic coverage. But Obamacare does not permit it unless you are under 30. And why do 60-year-olds need maternity care coverage? Why does everyone need insurance covering substance abuse therapy or mental health?

They don't.

But because of MacDonough's opinion, they might have to buy the extra coverage or have no insurance at all.

Sen. Ted Cruz asks the key question: Why listen to her?

By a simple majority, the Senate Republicans can overrule the decision of the parliamentarian and Obamacare reform will likely pass and be effective.

All the problems conservatives have with the proposed bill by Paul Ryan are due to its failure to cut the list of services in deference to the parliamentarian's likely ruling. The house speaker dares not pass a bill the Senate can't, so Ryan didn't touch the required services list. That led to CBO's pessimistic report about the number of people who would be uninsured and the high cost of the Ryan replacement.

Sweep aside Elizabeth MacDonough's ruling and it all goes away.

Who died and left her in charge?

Dick Morris, who served as adviser to former Sen. Trent Lott (R-Miss.) and former President Clinton, is the author of 16 books, including his latest, Screwed and Here Come the Black Helicopters.